The present invention relates in general to a method and apparatus for recovery and launch of marine structures onto and from the deck of ships, and more particularly to methods and apparatus for recovery and launching of barges, barge-like craft, Single Anchor Leg Mooring (SALM) bases, ships, boats, small craft and other marine structures onto and from the deck of host ships, such as cargo ships, tank ships and barges, in a timely controlled and safe manner, relevant to the areas of marine construction, off shore oil development, marine transportation, salvage, and military and commercial rapid deployment and rapid logistics support.
Heretofore, the primary methods for launching and recovery of marine structures such as SALM bases, barges and similar craft and the like, have involved the use of wet or floodable wells, such as floating drydock structures, or the use of support devices such booms, davits, cranes, beam climbers, and articulating structures. More recently, wedge shaped beams have been employed to launch and recover a SALM base, but such wedge shaped beam structures were pivoted at one side of the ship and were raised and lowered at the other side of the ship using a goal post type of structure. The wedged beams extended on beam climbers to the waters edge, and another set of beam climbers walked in and out on the upper wedge beam to effect recovery and launch of the SALM base.
These earlier methods of launching and recovery of marine craft required equipment with large capacities, in the case of booms, cranes, davits and like structures, to effect a recovery or launch. The well or wet deck type of structure required a significant modification of the host ships hull, using a significant amount of volume that could otherwise be devoted to cargo. The wedge shaped beam structures pivoted at one side of the ship for raising and lowering, to launch and recover a SALM base, requires a heavy structure, a large number of hydraulic controls, hoses and fixtures, and a large amount of time is consumed in performing the launch and recovery operations. Also such structures have demonstrated a tendency to launch the SALM base or barge unexpectedly.
An object of the present invention is the provision of a novel launch and recovery system and method for launching and recovering water craft from and onto the deck of a host ship or the like, which is simple in both fabrication and construction, and is flexible in that it can be installed on a wide variety of hull forms and incorporate a number of optional and diverse configurations, and is capable of being powered by a variety of different power sources. In one form of the invention, a hinged beam launch and recovery system is provided which can be installed taking advantage of the existing ship's structure and operating systems. The beam and supporting structure of this launch and recovery system is fabricated of common shapes and materials in lesser quantities than other systems, and involves less weight and lower fabrication and installment costs. The beam angle is adjustable during installation to accommodate the hydrostatic and operational characteristics of the ship. The hinged beams are configured to swing inboard about an axis perpendicular to the inclined plane defined by the craft supporting and guiding inclined surfaces of the stationary wedge beam sections and the hinged beams forming an outboard continuation of that inclined plane. The beam structures are configured to minimize the loss of cargo volume while maintaining hull girder strength.
The hinged beam configuration of the launch and recovery system is provided which permits diverse arrangements of the hinged beam, hinged block, deployment method, and securing mechanisms. The hinge beam may be swung or deployed in several ways, using gravity, block and tackle, hydraulic cylinders, gearing or other methods. This flexibility permits taking advantage of the ship's existing outfitting, and securing of the hinged beam may be by pin, bolt, latch, detent, welding or other known methods or combinations of methods. The hinged beam configurations of the present invention does not require heavy pivot blocks at "goal posts" or other beam lifting devices. This enables the load of both the launch and recovery structure and the recovered craft to be evenly distributed as opposed to being concentrated. In a preferred form of the system, the beams are fitted with low friction material, and when thus fitted, provide particular advantage on a tank ship or other ship where heat and spark generation needs to be avoided.
The system of the present invention may be described generally as a system to launch and recover marine vessels, herein sometime referred to as a secondary water craft or recovered vessel, brought onto the deck of a mother vessel or host craft. The secondary craft or recovered vessel is connected to a trolley assembly by a suitable connection mechanism, and the trolley assembly is free to slide up and down a skid beam, which has a liner which serves to reduce the friction between the trolley and the skid beam, and between the recovered vessels bottom and the skid beam. The trolley is pulled up the skid beam by means of a rope or cable attached at one end to the trolley and at the other end to a pulling assembly, which may consist of linear pullers, winches, and other known pulling devices, and such rigging as may be needed. The skid beams provide as surface to support the recovered vessel when the mother vessel or host craft is in transit, and also provide a continuous inclined surface extending to below the water line to allow the launch and retrieval of the recovered vessel. The skid beams include a stationary or fixed skid beam section and a movable skid beam section extended out beyond the side shell of the host craft in the form of hinged beams connected to each respective fixed skid beam, which hinge out about the generally vertical hinge axis perpendicular to the fixed skid beam surface. By inclining the ship, the outboard ends of the extended skid beams can be lowered below the water level.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating preferred embodiments of the invention.